Manufacture of resistor rods with thickened portions



Oct. 14, 1930. EGLY 1,778,665

MANUFACTURE OF RESISTOR RODS WITH THICKENED PORTIONS Filed Dec. 31, 1926 Patented a. 14, race UNITED STATES PATENT. OFFICE GEORG EGLY, DI? BERLIN, GERMANY, ASSIGNOR T0 GEBB'U'DER SIEMENS & 00., OF BERLIN-LIGHTENBERG, GERMANY, A CORPORATION OF GERMANY- MANUFACTURE OF RESISTOR RODS WITH THICKENED PORTIQNS Application filed December 31, 1926, Serial No. 158,392, and in Germany April 10, 1928.

My invention relates to the manufacture of resistor rods with thickened portions.

It is well known to thicken or enlarge resistor rods in certain places, particularly at the terminals at which they are connected in circuit, in order to reduce the resistance and consequently heat developed at those places. It was hitherto customary to bring about the desired thickenin or increase in diameter of 0 the rods by pushing short pieces of tube, collars or bushings over them and fixing these members in place by means of a suitable bonding material. This method of producin the thickened laces or enlargements is, lE- ever, unreliable and diflicult. It has in particular been found in practice that the contact resistance between the central core rod and the collar or bushing is very variable.

My invention consists in laterally applying to the resistor rod at the current terminals at which it is to be thickened, enlarged or increased in diameter, bodies consisting of conductin material the attachment surfaces of which have substantially the same shape or configuration as the surface of the resistor rod and interposing a layer of a suitable paste,

or bonding material between them. It is then unnecessary to slip as heretofore the enlarging bodies of conducting material over the core rod, and they are simply applied to the sides of the rod. This may be effected by coating the individual conducting bodies or the core rod or both of them with the paste or the like and by pressin the parts together. In this way the paste or onding materialis uniformly distributed between the parts to be combined and-the pressure applied ensures a particularly intimate connection between them. The conductivity of the thickened portionof the rod obtained in this manner is very uniform and permits of a reliable manufacture on a large scale, scrap being almost entirely avoided. According to my invention partsof a longitudinally split tube of a similar material as, or referably of a better conducting material tlian the core rod is chosen as a suitable body of conducting material. In many cases the halves obtained by splitting a tube lon itudinally are most conveniently employe for the purpose. For binding the applied conducting body with a rod a plastic material or paste'is employed as bonding material which is similar in its qualities to that of which the conducting body is constructed or consists of the same material. These enlarged terminals of the resistor rod may be consolidated and finished by again baking or burning the rod with the applied bodies.

In the drawing aflixed hereto an embodie ment of my invention is illustrated by way of example.

In the drawing Fi 1 shows an end-elevation ofa resistor rod t ickened in one place according to my 6:. invention, and I Fig. 2, a side-elevation of the same.

Like parts are indicated b like letters of reference in both figures of t erawing.

Referring to the drawing A is the resistor rod to which are applied the two halves B and C of a tube obtained by splitting a short sleeve lengthwise. Prior to the application of the parts B and C the rod A has been coated with a bonding substance D at the place at which it is desired to thicken the diameter of the rod. 1 The rod with the applied pieces is then again subjected to a. baking process or other heat treatment and thus consolidated and finished. 30

Such enlarged terminals may, as a matter of course,be produced at the ends of the rods as well as in other, places. They may, for instance, be produced at a certain dis-.

tance from the endsof the rod and the con- 5 ductivity' of the ends may be increased by ametal coating which coating may extend to the terminal of the .rod. 'In this way forms of rods are obtained which are suitable for many purposes. In particular it is ossible in this way to produce comparative y light rods which are suitable for use atvery high temperatures and possess at the-same time a good metallic contact at their ends. The 1 metal coating is efiectivelyprotected against the effect of the high rod temperatures by the thickened or enlarged portion located in front of it.

Various modifications and changes may be made without departing from the spirit 10c mentary terminal elements of conducting material and of similar configuration as they 7 and the scope of the invention, andI desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art. U

I claim as my invention:

Method 'of producing thickened terminal portions on a resistor rod, consisting in applying a thin coating of pasty resistor material to said rod portions pressing complerod portions laterally against the coated portions and then firing said rod portions to produce a firm conductive bond betweenthe red portions and the terminal'elements.

In testimony whereof. I afix m1 signature. 1 GEOR EGLY. 

